Nailing machine



2 Sheets-Sheet l A. E. CAlRATTl NAILING MACHINE Aug. 27, 1968 Filed Jan. 25, 1967 Imam m2.- mvrw/ur 1?. 09/247 Aug. 27, 968 A. E. CAIRATTI NAILING MACHINE 533 zaza 2 m w 1 IN N s U 3 t A 2 m u N a A Filed Jan. 23, 1967 M FIGA United States Patent 3,398,648 NAILING MACHINE Anthony E. Cairatti, Herrin, lll., asslgnor to Werner Schafroth, Herrin, 111. Filed Jan. 23, 1967, Ser. No. 610,970 9 Claims. (Cl. 91-417) ABSTRACT OF THE DISCLOSURE A nailing machine in which the valve is mounted in a driving piston mounted in a stationary cylmder over whose top no pressure fiuid is directed to force the plston downwardly, so that pressure fluid does not spill 1n over the top of the cylinder and the cylinder does not move in a vertical direction, but the piston moves down because of the valve within the piston itself.

This invention relates to an improved nailing machine, and in particular, to a power actuated nailing mach ne whose head is relatively short in height. Such a machine is used to drive corrugated fasteners, nails, and heavy and long staples. Power actuated nailing machines have been used in the past, but such machines have been relatively tall with numerous parts therein. Many of such past machines contained a cylinder which moved vertlcally and many operated through the movement of valve means to open the entire top of said cylinder to allow pressure fiuid to spill over the top edge thereof into the cylinder to drive the piston downwardly.

One of the principal objects of the present invention is to provide a nailing machine with a fixed cylinder therein whose top portion is always closed to driving fluid, said machine having a relatively short head. Another object is to provide a new and improved construction for supplying driving fluid to a stationary cylinder and to the piston to be driven. Another object is to provide valve means within the piston itself, said valve means when open allowing pressure fiuid to enter the chamber above the piston to drive the piston downwardly. Another object is to provide a valve chamber within the piston itself which allows the piston to move downwardly when said valve chamber is connected to atmosphere and which allows the piston to move upwardly toward its upper position when under the same pressure as in the reservoir.

These and other objects and advantages will become apparent hereinafter.

The present invention is embodied in a nailing machine having a piston therein, a stationary cylinder whose top is closed at all times to driving fluid, said piston being positioned within said cylinder and carrying a valve to permit the piston to be driven and to effect its return.

The invention also consists in the parts and in the arrangements and combinations of parts hereinafter described and claimed. In the accompanying drawings which form part of this specification and wherein like numerals and symbols refer to like parts wherever they occur:

FIG. 1 is a vertical longitudinal cross-sectional view of a nailing machine embodying the present invention showing the piston in the upper position,

FIG. 2 is a view similar to FIG. 1 but showing the trigger in its upper position and the piston in its downward position,

a FIG. 3 is a cross-sectional view taken along the line 33 of FIG. 1,

FIG. 4 is a fragmentary cross-sectional view taken along the line 4-4 of FIG. 3 with the piston in its upper position, and

FIG. 5 is a view similar to FIG. 4 but showing the piston moving downwardly.

The nailing machine N which embodies the present 3,398,648 Patented Aug. 27, 1968 invention is provided with the usual safety means (not shown) and a magazine M. These may be of the type I well-known and used in the past, such as shown in the Schafroth and Cairatti co-pending applications Ser. No. 399,152 and 413,045. Their details will not be shown or described here, since they are well-known in the art.

The nailing machine N has a head H with a handle 1 and a trigger 2, and a magazine M for feeding nails to the head H in order to be driven by a power actuated driving blade 3. The handle 1 has a leg 4 mounted on a pin 5 on a bracket 6 secured to the magazine M. The handle 1 is hollow to form a storage reservoir 7 with an opening 8 in its rear portion for receiving a source of com-' pressed air or pressure fluid. The hollow handle 1 forms a substantial portion of the reservoir 7.

The head H comprises an upstanding casing 9 with a plate 10 and cap 11 sealably secured thereto. The head H contains a stationary vertical cylinder 12 having an opening 13 therein near the central portion of the cylinder 12. This opening 13 is slightly above the median line in the form of the invention illustrated. The cylinder 12 has an upper wall 14 whose diameter is slightly greater than the diameter of the lower wall 15, there being a shoulder 16 therebetween adjacent to said opening 13. Extending rearwardly from the upper Wall 14 is a partition 17. I The trigger 2 is pivotally mounted on a pivot pin 18 on the casing 9 and is adapted to move a stem 19 vettically, said stem 19 being slidably mounted in a'lower opening 20 in the handle 1 and an aligned upper opening 21 in said casing 9 adjacent to said partition 17. The stem 19 has an O-ring 22 in its lower portion 'to seal the opening 20 and prevent leakage from the reservoir 7 through the lower opening 20. The stem 19 has a shoulder or seat 23 and a reduced upper portion 24 thereabove with a cross-passage 25 and a vertical exhaust port 26 therein. O-rings 27 and 28 are mounted in grooves in said reduced upper portion 24, whose upper end is charnfered and forms an exhaust valve 29. A stationary collar 30 is mounted in-the upper opening 21 below the plate 10, which has openings 31 therein but which is in fixed relation with the upper end 32 of the cylinder 12. The collar 30 slidably receives the reduced upper portion 24 of the stem 19 and has an annular external groove 33 and a cross-passage 34 and large internal diameter to form a vertical passage 35 between said collar 39 and said reduced portion 24. An O-ring 36 fits in a groove in the upper portion of said collar 30. A piston 37 is mounted within the cylinder 12. The piston means 37 comprises an upper piston or portion 38 and a lower piston or portion 39 of smaller diameter connected by a connector or pedestal 40 with an opening 41 therein. The lower piston 39 has a lower piston plate 42 attached thereto by means of a screw 43 having a head 44 positioned within the opening 41 in the pedestal 40. The lower piston 39 has a suitable O-ring 45 around its periphery. The lower piston plate 42 has the downwardly extending driving blade 3 connected thereto. The pedestal 40 supports a cage 46 having an enlarged upper portion 47 which slides on the upper wall 14. An O-ring 48 is positioned in a groove in the upper portion 47. The cage 46 has lateral openings 49 therein and is provide-d with a slidable double diametered valve 50. The valve 50 has an O-ring or seat 51 and a lower O-ring 52 and is biased upwardly by a spring 53 on a retainer 54 and sleeve 55 into sealing relation with a valve seat 56 held in position in said cage 46 by a ring 57. The valve seat 56 is provided with a suitable O ring 58. The valve seat 56 receives the upper O-ring 51 in the valve 50, which also has the lower O-ring 52 therein. The sleeve 55 has vertical passages 59 therein and an O-ring 60 thereabove. The effective area of the bottom of the valve 50 is greater than the effective area of the top of the valve 3 50 inwardly of the O -ring 51, so that if the valve 50 is exposed to the same pressure both from above and below, the valve 50 tends to remain in its upper position against the valve seat, as shown .in FIG.. 1. Therefore, the valve 50 may be said to be a double-diametered valve slidably mounted within the upper portion 39.

The cylinder 12 contains an upper chamber 61 above the upper piston 38, a middle chamber 6 2 between the upper piston 38 and lower piston 39, and a lower chamber 63 beneath the lower piston 39. A valve chamber 64 is formed in the upper piston 38 beneath the valve 50in the cage 46.

The cap 11 is provided with a cap chamber 65 above the plate which communicates with a hole 6'6 in the plate 10 and a chamber 67 above the partition 17. The cap 11 receives the enlarged upper end 68 of a downwardly extending tube 69 having a passage 70 therein and an O-ring 71 therearound. The cap 11 is also provided with a seat 72 for the exhaust valve 29 and a forwardly directed exhaust passage 73 on the top thereof. The tube 69 extends downwardly through the double diametered valve 50 in sliding relation thereto to a point slightly short of the head 44 of the screw 43 so that the lower end 74 of the tube 69 is always open.

The casing 9 is provided with a bumper 75 at the bottom 76 of the cylinder 12 which has a bottom open ing 77 therein and an exhaust port 78 for allowing air beneath the lower piston 39 in the lower chamber '63 to be expelled rapidly so as not to resist the downward movement of the lower piston 39.

In operation, the nailing machine N is suitably attached to a source of compressed air at about 80 pounds per square inch and the magazine is loaded with the proper nails. The parts are shown in their inoperative position in FIG. 1. In this position, compressed air from the reservoir 7 is free to enter the middle chamber 62 in the cylinder 12 and is free to enter the chamber 67 above the partition 17 and the cap chamber 65 in the cap 11. The spring 53 is strong enough to keep the double diametered valve 50 up against the valve seat 56 (FIG. 1). The opening 26 in the exhaust valve 29 is effectively closed due to the position of the O-ring 28 on the reduced portion 24 of the stem 19.

When the trigger 2 is lifted (FIG. 2), the stem 19 is raised to allow the normally pressurized valve chamber 64 within the cage 46 of the upper piston 38 beneath the valve 50 to exhaust to atmosphere through the passages 59, the tube 69, the cap chamber 65, the hole 66, the chamber 67 above the partition 17 through the crosspassages 34 in the collar 30, the vertical passage 35, by the O-ring 28 and up through the cross-passage 25 and vertical port 26 in the exhaust valve 29 and out through the top exhaust passage 73. This forces the inner valve 50 down to break its seal from the valve seat 56 and allows the pressure fluid from the reservoir 7 and within the middle chamber 62 between the upper piston 38 and lower piston 39 to enter the openings 49 in the cage 46 and the space 80 between the O-ring 51 and the valve seat 56 thereby driving the entire piston 37 down. This allows pressure fluid to enter the upper chamber 61 above the upper piston 38 to drive the entire piston 37 downwardly to the position shown in FIG. 2. The parts remain in this position as long as the trigger 2 is lifted.

When the trigger 2 is released, the stem 19 moves down thereby connecting the reservoir 7 with the chamber 67 above the partition 17 and the cap chamber 65, which are connected through the hole 66, to allow pressure fluid to move downwardly through the tube 69 to reestablish pressure in the valve chamber 64 containing the spring 53 beneath the valve 50, thereby moving said valve 50 upwardly, together with the force from the spring 53, until the O-ring 51 seats on the seat 56. When the valve 50 is closed, that is, when the O-ring 51 contacts the seat 56, pressure fluid from the reservoir 7 works on the under sides of the cage 46 and upper piston 38 to raise it to its top position against or adjacent to the bottom surface of the plate 10 (FIG. 1). The upward forces on the upper piston 38, both externally and from within the valve chamber 64 beneath the valve 50, are such that they overcome any downward force on the lower piston 37 whose effective area is less than area of upper piston 38.

Thus, the cylinder 12 does not move and is always closed at its upper end 32. No pressure fluid ever flows over the upper end 32 of the inner cylinder 12 to drive the piston 37 down. Instead, the piston 37 moves down because of the opening between the seat 56 and the O-ring 51 in the valve 50 within the upper piston 38 itself.

This invention is intended to cover all changes and modifications of the example of the invention herein chosen for purposes of the disclosure which do not constitute departures from the spirit and scope of the invention.

What is claimed is:

1. In a fastener driving apparatus compriting a housing defining a reservoir to which pressure fluid is continuously applied, a stationary cylinder mounted in said apparatus, an opening connecting said cylinder and said reservoir, piston means slidably mounted within said cylinder, said piston means having an upper portion and a lower portion with a connector connected therebetween, said lower portion always being positioned below said opening, valve means movably positioned in said upper portion, said valve means being open when said piston means is being driven downwardly to permit pressure fluid from said reservoir to act on the upper surface of said upper piston, said valve means being closed when said piston means is being moved upwardly to return said piston means to its upper position, said valve means having a valve chamber therebelow and within said piston, said valve means being closed when said pressure in said valve chamber is at substantially the same pressure as the pressure in the reservoir, said valve means being open when said valve chamber is connected to atmosphere, said cylinder having an exhaust port therein in the bottom portion thereof below said cylinder to exhaust air below said piston means during its downward movement.

2. The combination set forth in claim 1 wherein said valve means within said upper portion is normally closed and is open only when said apparatus has been actuated to drive the piston means downwardly.

3. The combination set forth in claim 1 wherein a stationary tube extends downwardly through said upper portion for exhausting the valve chamber to atmosphere, thereby permitting said valve means to move downwardly to permit pressure fluid to act in a downward direction upon the entire effective top area of said upper portion.

4. The combination set forth in claim 1 wherein said cylinder is always closed at the top except for an exhaust port to permit pressure fluid above said piston means to be exhausted to atmosphere when said piston means is moving upwandly.

5. The combination set forth in claim 1 wherein said valve means within said upper portion is a double diametered valve slidably mounted within said upper portion.

6. The combination set forth in claim 1 wherein the effective area of the lower surface of the upper portion of said piston means is greater than the effective area of the upper surface of the lower portion of said piston means, so that when said valve means is in its upper or closed position the pressure fluid from said reservoir causes said piston means to move upwardly.

7. The combination set forth in claim 1 wherein said opening is positioned in said cylinder wall adjacent to said reservoir slightly above the middle of the cylinder.

8. The combination set forth in claim 1 wherein pressure fluid from the reservoir is permitted to pass from beneath said upper portion through said upper portion between the valve means therein and a seat in said upper portion to act on the entire effective area of said upper 3,398,648 5 p 6 portion and said valve means and wherein said pressure References Cited fluid from said reservoir constantly acts upon the upper UNITED STATES PATENTS surface of said lower portion of said piston means.

9. The combination set forth in claim 1 wherein the 2,960,067 11/1960 OSPOme 91417 diameter of said lower portion of said piston means is 5 3,051,135 8/1962 Smlth 91-417 slightly less than the diameter of said upper portion of Said piston means. PAUL E. MASLOUSKY, Przmary Examiner. 

